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    CWG Issue 322</TITLE>
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<P><EM>This is an unofficial snapshot of the ISO/IEC JTC1 SC22 WG21
  Core Issues List revision 118b.
  See http://www.open-std.org/jtc1/sc22/wg21/ for the official
  list.</EM></P>
<P>2025-09-28</P>
<HR>
<A NAME="322"></A><H4>322.
  
Deduction of reference conversions
</H4>
<B>Section: </B>13.10.3.4&#160; [<A href="https://wg21.link/temp.deduct.conv">temp.deduct.conv</A>]
 &#160;&#160;&#160;

 <B>Status: </B>CD1
 &#160;&#160;&#160;

 <B>Submitter: </B>Jason Merrill
 &#160;&#160;&#160;

 <B>Date: </B>14 Nov 2001<BR>


<P>[Voted into WP at April 2003 meeting.]</P>



<P>Consider:
<PRE>
  struct S {
    template &lt;class T&gt; operator T&amp; ();
  };

  int main ()
  {
    S s;
    int i = static_cast&lt;int&amp;&gt; (s);
  }
</PRE>
13.10.3.4 [<A href="https://wg21.link/temp.deduct.conv">temp.deduct.conv</A>] says that we strip the
reference from <TT>int&amp;</TT>, but doesn't say
anything about <TT>T&amp;</TT>.  As a result, <TT>P</TT> (<TT>T&amp;</TT>)
and <TT>A</TT> (<TT>int</TT>) have incompatible forms
and deduction fails.</P>

<P><B>Proposed Resolution (4/02):</B></P>

<P>Change the last chunk of 13.10.3.4 [<A href="https://wg21.link/temp.deduct.conv#2">temp.deduct.conv</A>] paragraph 2 from
<BLOCKQUOTE>
     If <TT>A</TT> is a cv-qualified type, the top level cv-qualifiers
     of <TT>A</TT>'s type are ignored for type deduction.  If
     <TT>A</TT> is a reference type, the type referred to by
     <TT>A</TT> is used for type deduction.
</BLOCKQUOTE>
to
<BLOCKQUOTE>
     If <TT>A</TT> is a cv-qualified type, the top level cv-qualifiers
     of <TT>A</TT>'s type are ignored for type deduction.  If <TT>A</TT> is a
     reference type, the type referred to by <TT>A</TT> is used for
     type deduction.  If <TT>P</TT> is a reference type, the type
     referred to by <TT>P</TT> is used for type deduction.
</BLOCKQUOTE>
</P>

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